|Sewage Requirements of Merchant Shipping Regulations:
Sewage equipment is required only by vessels of >400 GRT or <400 GRT if certified to carry more than 15 persons and if engaged in international voyages. The requirements for sewage equipment will therefore apply to mobile drilling units or other vessels (e.g. FPSO) on international voyage.
Sewage discharge (from applicable ships) is:
- Prohibited within 3 miles of land.
- If appropriate sewage treatment plant (see below) is on board, discharge may occur if > 3 miles from land.
- If disinfected/comminuted sewage has been kept in a holding tank, discharge should only be made while on route and proceeding at > 4 knots.
- If no treatment facilities are on board, sewage may only be discharged if > 12 miles from land.
All ships to which the sewage requirements apply must have at least one of the following on board:
- A sewage treatment plant which complies with the Merchant Shipping (Marine Equipment) Regulations 1999 as amended, or
- A sewage comminuting and disinfecting system which meets the standards for such systems set out in MSN 1807, and is fitted with facilities for temporary storage of sewage which meet the standards set out in that MSN, or
- A holding tank for the retention of sewage which meets the construction standards set out in MSN 1807, has sufficient capacity and has a visual indicator of the amount of its contents.
See MGN 385 (M+F) Guidance on the Merchant Shipping (Prevention of Pollution by Sewage and Garbage from Ships) Regulations 2008 for further information.